Friday, January 25, 2013

Many people (almost entirely non-scientists or non-climatologists) inaccurately claim that the scientific community either has not or cannot reach consensus on the topic of anthropogenic climate change (i.e., global warming). This claim has become a worn and weary diatribe used by some people, yes, I will even go as far as to say "conspiring men" who are trying to muddy the waters on a topic that is accepted nearly universally by the practicing scientific community.

Why do people believe these conspiring men? Because it happens to fit their pre-existing notions or opinions on climate, economy, religion, or plays to their benefit in terms of vested interest (e.g., oil industry).

The bottom line is that the scientific community has near unanimous consensus on the topic of climate change. By the way, what proportion of scientists would it take to constitute a consensus? 50.1%, 60%. 75%, 80%, 90%, 95%, 98%, 99%, 100%?

I think that we can all agree that reaching a 100% consensus on any scientific theory is nigh unto unattainable, but was exactly what was discovered in a study carried out in 2004, and consensus has continued to strengthen since then.

In 2004, a study by the well-resepcted UC San Diego sociologist Naomi Oreskes was published Science, America's most prestigious scientific journal (http://leisureguy.wordpress.com/2007/09/04/the-scientific-consensus-on-global-warming/). Results described in that study showed that NONE of the 982 peer-reviewed scientific papers on the topic of climate change published between 1993 and 2003 disputed the conclusion of anthropogenic climate change.

Be advised that the formatting and layout of these kinds of papers are intended to make them appear to be credible sources of information, but they are not comparable to peer-reviewed publications in professional scientific journals.

Back to the Heartland Institute paper...it reported moderate agreement on some topics, but significant disagreement on others. There are, however, several points of concern related to this report and others like it. The most important concern is that this report cannot be considered verifiable scientific information since it was never subjected to peer-review and was not published in a reputable scientific journal. Another note of concern is the source of the paper itself. It is a product of "The Heartland Institute". Investigative research into public records shows that this institute and others like it are engaged in carrying out an active campaign to cloud the public's perception of well-documented scientific conclusions regarding climate change. If you have questions about this I strongly recommend that you take a look at the book "Merchants of Doubt" by Naomi Oreskes (http://www.merchantsofdoubt.org/)

Getting back to the original point of the posting. There is clearly near unanimous consensus among climate scientists (98%+) that climate change is happening and more than 90% confident (IPCC report, 2007) that the current trend of global warming is being driven mainly by anthropogenic forcing factors, including greenhouse gas emissions and land-use changes, among other activities.

So what does scientific lack of consensus on verifiable scientific observations on this topic look like? It looks like this:

Every year, groups of climatologists working independently in the USA, Great Britain, Japan, and other locations around the world, collect temperature data and generate average annual observed temperatures. They can then plot their data onto one graph, as shown above, and see where differences and variations among their results are. If there is any lack of consensus it is that some data show slightly warmer temperatures some years, while others show slightly cooler ones, but within a range of acceptable statistical variability, all the data produce the same long-term trends. In other words - consensus.

Similar work is done by climatologists investigating causes (also referred to as climate forcing factors), and they also nearly universally conclude that without human-produced effects, we would not currently be experiencing a warming trend. Instead we would be experiencing a gradual cooling trend.

So whenever you hear someone parroting some out of date or completely unsupportable fallacy that there is no scientific consensus on anthropogenic climate change, ask them about their source of information. It will inevitably originate in some non-scientific think tank or media outlet that clearly has an agenda that benefits if people do not understand that there is scientific consensus on climate change and that we had better get busy doing something about mitigating the effects of climate change.

Rexburg, Idaho, experienced quite a cold spell throughout most of January. How cold? Read on.

On an aside, it kind of baffles me why low temperatures experienced in the upper midwest makes the national news, while extreme cold weather here does not. I guess it's because most of the people in the USA are familiar with Idaho, you know, that's where they grow potatoes, and it's the capital of Montana, or something like that. That's part of living in a national backwater I suppose. Anyway...

According to data from the National Weather Service, and put into graphical form by Weather.com, The average January high temperature for Rexburg, ID, is 29oF, and its average low temperature is 13oF (see below).

Here are the observed temperatures for Rexburg, ID, January 1-23, 2013.

A little number crunching shows that through 1/23/2013 our observed average high temperature was 18.5oF. That's 11.5oF lower than our average high temperature for the month. The average low temperature here was -2.7oF. That's nearly 16oF below our monthly average.

Yep, it was cold, cold, COLD, in Rexburg, and lots of other places this January.

Fortunately we are experiencing a change in the weather here now. Today's weather? Cloudy and RAIN...!? Yep, rain!

Tuesday, January 15, 2013

It's been quite a while since I gave you an update on what's happening in the Arctic.

First of all, the Arctic Oscillation shifted recently from its Positive Phase to its Negative Phase; it has been mostly in the Positive Phase since the 1970s . During the Positive Phase there is a large low pressure region dominating the Arctic, but during the Negative Phase there is a large high pressure system there. This switch means that masses of cold Arctic air are more likely to push south and perhaps stay longer than they used to. This is especially true for western North American. This also helps explain the ice-box conditions we have been experiencing lately in the mountain west.

In other news, the Arctic Ocean sea ice freeze is well under way. After the record ice melt of the summer of 2013, climatologists are keeping an interested eye on 2013's freeze up. As the map below from the NSIDC.org shows, sea ice extent is at or sightly above normal in the Bering Sea and beyond the Kamchat peninsula. At the same time, it is well below historical averages east of Scandinavia and south of Greenland.

If you recall, the Bering Sea produced above average sea ice coverage last year, and the lower than average sea ice in east of Greenland also lagged behind historical averages.

Though sea ice production and sea ice extent are still rising - as is to be expected this time of year - current sea ice extent is about 1 million km2 below historic averages (see the graph below from the NSIDC.org)

FYI - The last time sea ice cover reached or exceeded the historic average for this time of year was in 1998 - yep, 15 years ago. Every year since then, mid-January sea ice extent has been below average. The take home message is that the Arctic continues to warm, and that sea ice extent continues to decline (on average) as the years go by.

Monday, January 14, 2013

The western United States experienced an extremely mild, dry winter during 2011-12. This year (2012-13), however, things are different - it's cold, cold, cold! and wetter than last year, too.

For example, where I live in SE Idaho, we have been experiencing low temperatures in the -10 to -20oF range over the last week or so.

Why is it so much colder than last year?

Last year's mild winter can be explained in part by ongoing global warming, but prevailing weather conditions over the Arctic also matter.

There is something called the Arctic Oscillation (AO). The AO has two phases, a positive and a negative phase. During the Positive Phase of AO, low pressure sits over the Arctic and a high pressure system dominates around 45oN. During the Negative phase of AO, the opposite occurs; a high pressure system dominates the Arctic and low pressure exists around 45oN.

The bottom line is that the AO can switch between its positive and negative phases over a matter of weeks to decades. The dominating phase of AO can have a significant impacts on the weather over the northern hemisphere.

(Images courtesy of NSIDC.org)

The image above left shows the effects of the "Positive Phase of Arctic Oscillation". During the positive phase (low pressure system over the Arctic) masses of cold Arctic air stay farther north, and the western USA stays warmer and drier than usual. At the same time, coastal Eastern Canada gets colder air than usual. During the Positive phase the North Atlantic storm track can also move farther north than usual, bringing cold, wet winter weather to northern Europe. According to NSIDC.org, we have been experiencing mainly the positive phase of AO since the 1970s.

The image above right shows the effects of the "Negative Phase of Arctic Oscillation." During the negative phase (high pressure over the Arctic), low pressure is much more common around 45oN, and this phase recently developed. During the negative phase colder, wetter air masses than usual are pulled farther south by the low pressure system over western North America. Along with this we normally see the Atlantic storm track pushed farther south, bringing precipitation to the Mediterranean instead of northern Europe.

There are, of course, many other oscillating weather patterns that contribute to conditions we experience, but the AO is one recently switched phases.

Global Warming also plays an important role in generating weather. Even though the Arctic is cold, much more heat than normal is stored there, and it has to go someplace. One thing this does is increase the amount of atmospheric activity and can contribute energy to the polar jet stream, pushing it farther south than usual. The map below shows the jet stream track for 14 January 2013:

The map above shows the jet stream pushing as far south as northern Mexico. My son happens to be there, and he reported recently that they are experiencing freezing temperatures and even snow!

Knowing something about the Arctic Oscillation effects of global warming help us understand weather we experience.

Monday, January 7, 2013

Every month or so I get a weather summary/update from our local weather guru, Lee Warnick. He enjoys tracking the weather...I enjoy tracking climate.

Anyway, his latest weather news release to the "Rexburg Weather Group" was quite the eye-opener. I mean it shouldn't have been much of a surprise given the un-Idahoanly mild winter we had in 2011-2012, but the effects of global climate change are being felt everywhere, even here in SE Idaho.

Here are some highlights from his weather summary of 2012:

Average annual high temperature data for Rexburg, Idaho (n=41 years of temperature data)

Average annual high temp = 56.25oF

2012 average high temp = 59.36oF

Departure from average = +3.11oF

This is the highest annual average temperature on record for Rexburg, Idaho

Average annual low temperature data for Rexburg, Idaho (n=41 years of temperature data)

Average annual low temperature = 30.59oF

2012 annual low temperature = 34.12oF

Departure from average = +3.53oF

This was this highest annual low temperature average for Rexburg, Idaho ever

>90oF days

Average number of 90oF days = 15.6

2012 number of 90oF days = 32

2012 had more than twice the historical average of 90+oF days!

<0oF days

Average number of days with below 0oF temperature = 17.5

2012 number of days below 0oF = 1...that's right only ONE! Unbelievable!

Windy days in Rexburg, Idaho...a place already known for its wind

Annual average number of windy days = 65.6

2012 number of windy days = 104

Yep, that's 1.6 times more windy days than the historical average.

The previous record number of windy days/year was 95 in 2011 (also a record at the time)

Daily temperature records

High daily temperature records - there were 45 new daily temperature records set in 2012

Low daily temperature records - there were 6 new daily low temperatures set in 2012.

If we were in a normal temperature year we would predict roughly equal numbers of high and low temperature records to be set, but in 2012 high temperature records to low temperature records were set at a rate of 7.5:1.

What does all of this mean?

It means that 2012 was the warmest, windiest year on record for Rexburg, Idaho.

Is this an evidence of global warming?

It is statistically difficult to tie an individual weather event, such as one warm year or one windy year, to global warming. But, what we can say with confidence is that the current trend of global climate change makes years like these more likely to occur than in the past, and that the observed elevated temperatures and increased number of windy days are also consistent with climate models of ongoing global warming.

We can also be confident in saying, like it or not, that there will be cooler years than 2012 and warmer years than 2012 in the future, but that we are almost certainly going to see more warmer years than cooler years as long as the current trend of global warming continues.